Separate 3 eggs.,Beat whites until stiff.,Beat in 1/2 cup sugar; add yolks singley, beating throughly.,Stir in lemon juice. Fold in 1 cup heavy cream, stiffly beaten.,Roll vanilla wafers into fine crumbs.,Sprinkle 1/2 the crumbs in bottom of buttered freezing tray.,Pour in lemon mixture.,______,Serves 6.